Row 6 Selection, Arguments

CS Principles AP Prep
1

It seems that the Function Requirments section from the Survival Guide is at odds with Example 4 and maybe even the College Board’s Scoring Guidelines.

Code.org’s Survival Guide, Function Requirements (which received the point)

Selection means that a conditional, or if-statement, selects between two or more portions of your program to run. Iteration simply means repeating some behavior, as in a loop.

Code.org’s Survival Guide, Algorithm 4

function addPositives(list){
   var total = 0;
   var currentItem;
   for(var i = 0; i < list.length; i++){
      currentItem = list[i];
      if(currentItem > 0){
         total = total + list[i];
      }
   }
   return total;
}

College Board’s Scoring Guidelines

describe two calls to the selected procedure identified in written response 3c. Each call must pass a different argument(s) that causes a different segment of code in the algorithm to execute.

Question
If argument A causes line x to execute and
argument B prevents line x from executing, (example 4)
Does that satisfy “different segments of code in the algorithm to execute”?

2

It is my understanding from listening to people who actually know these things that yes, the absence of running a statement constitutes selection.

3

I agree. However, I think it will be easier for students to write about something happening rather than something not happening.

And, code.org should clear that up on their Survival Guide.

4

Hi @michael_campbel,

Thanks for bringing up this point! Like @jdonwells mentioned, from what we understand selection can mean that in one case a statement is run, and in another, the same statement is not. However, this would be a great question to pose on the College Board Forum [link].

As for our examples, I will keep this in mind when we update them for next year’s curriculum. With this being the first year the exam is being scored, we will have a lot better understanding of how the rubric is implemented as we head into next year.

Thanks again for bringing this up!
Cheers,
Ken